1. Field of the Invention
The present invention relates to an airbag apparatus installed in a vehicle to inflate and deploy mainly in order to protect an occupant in case of emergency.
2. Description of Related Art
An airbag apparatus is a safety apparatus that operates in case of emergency, such as a vehicle collision, and includes, for example, a bag-like cushion portion. The cushion portion is inflated and deployed by a gas, during an emergency, to receive and protect an occupant. Various types of airbag apparatuses are available depending on the installation position or application. By way of example, a side airbag is known which inflates and deploys from a side portion of a vehicle seat to a position immediately beside the occupant in order to protect the occupant in a side impact and a possible subsequent rollover (overturn).
The airbag apparatus includes a gas generating apparatus called an inflator and which supplies a gas to the cushion portion. The inflator is internally filled with a gas generating agent and is configured to combust the gas generating agent and eject the gas, for example, through a gas ejection port formed in an outer surface of the inflator, when a sensor or the like detects an impact. For the side airbag and the like, a cylindrical (cylinder-shaped) inflator is mostly used.
The cushion portion is divided into a plurality of small rooms (chambers) by sewing or the like. The division into the plurality of chambers allows an impact to be mitigated at a plurality of positions using the single cushion portion or allows the occupant to be restricted, improving occupant protection performance. Channels through which the gas ejected from the inflator flows are formed between the plurality of chambers to enable each of the chambers to inflate and deploy.
However, in an airbag apparatus with a plurality of chambers, for example, when the occupant touches the cushion portion, a reverse flow of the gas may occur between the chambers, making maintenance of the internal pressures of the chambers difficult. In the cushion portion, for example, the chamber positioned close to the gas ejection port of the inflator may have a high pressure, whereas the chamber positioned farthest away from the gas ejection port of the inflator may have a low pressure. In such a case, the gas flows reversely from the high-pressure-side chamber to the low-pressure-side chamber, making the maintenance of the internal pressure of the high-pressure-side chamber difficult.
In this regard, Japanese Patent Application Laid-open No. 2001-63502 describes an airbag with a connection hose provided between a first chamber and a second chamber to serve as a check valve. The connection hose includes an inner cloth disposed therein to separate a fluid passage between the first chamber and the second chamber from a pressure chamber connected to the second chamber. In the airbag, when the internal pressure of the second chamber is lower than the internal pressure of the first chamber, the inner cloth opens the fluid passage. When the internal pressure of the second chamber is higher, the inner cloth closes the fluid channel.
Japanese Patent Application Laid-open No. 2011-255714 describes an airbag with a duct portion disposed to allow a plurality of chambers to communicate with one another and an airbag check valve. The airbag check valve has a cylindrical portion sewn to the duct portion and a tongue-like portion formed at a leading end portion of the cylindrical portion. In this airbag, since the tongue-like portion is formed at the leading end of the cylindrical portion sewn to the duct portion, resistance offered when the gas flows in the reverse direction can be increased. Thus, the tongue-like portion is easily rolled into the cylindrical portion, and the channel of the check valve is easily blocked.
In the technique described in Japanese Patent Application Laid-open No. 2001-63502, the inner cloth disposed in the connection hose has a cylindrical shape, and parts of the inner cloth forming the cylindrical shape stick to each other to prevent the reverse flow of the gas from the second chamber to the first chamber. However, it is difficult to control the direction in which the parts of the cloth forming the cylindrical shape stick to each other. Thus, the technique is disadvantageous in reproducibility.
FIG. 8 and the like in Japanese Patent Application Laid-open No. 2011-255714 disclose a configuration of a check valve with a cylindrical portion and a tongue-like portion in which the tongue-like portion is stuffed into the cylindrical portion toward the center thereof to seal the channel. However, a change in internal pressure after the stuffing may cause the check valve to be collapsed.
With such problems in view, it is an object of the present invention to provide an airbag apparatus that prevents the reverse flow of the gas between the chambers to allow the internal pressures of the chambers to be maintained.